A conventional acoustic wave element will be described with reference to FIG. 10. FIG. 10 is a sectional view of a conventional acoustic wave element. Acoustic wave element 1 includes piezoelectric body 2, IDT electrode 3 provided on piezoelectric body 2 and exciting a main acoustic wave having a wavelength of λ, dielectric layer 4 provided on piezoelectric body 2 so as to cover IDT electrode 3, contact layer 5 provided on dielectric layer 4, and reactive portion 6 provided on contact layer 5 and reacting to a substance to be detected or a binding substance that binds with the substance to be detected.
In such conventional acoustic wave element 1, the main acoustic wave that is excited by IDT electrode 3 is a surface acoustic wave propagating on a surface of dielectric layer 4. However, since dielectric layer 4 is so thin that energy is distributed over a surface of dielectric layer 4, a problem is caused in which IDT electrode 3 is damaged by an external factor, and performance thereof deteriorates during use or during a manufacturing process of acoustic wave element 1.
For example, Patent Literature 1 is known as conventional art literature information related to the invention of this application.